Electric drilling apparatus



June 1930' c. CONTAL E.T AL 1,768,119

ELECTRI C DRILLING APPARATUS Filed Feb. 29, 1928 3 Sheets-Sheet 1 fig 1 .Iu11e24, 1930. c. CONTALETAL 1,768,119

11115011110 DRILLING APPARATUS Filed Feb. 29, 1928 s Sheets-Sheet s Patented June 24, 1930 UNITED STATES PATENT OFFICE CAMILLE CONTAL, OF ST. CLOUD, AND PIERRE KRETTLY, OF PARIS, FRANCE ELECTRIC DRILLING APPARATUS Application filed February 29, 1928, Serial The present invention relates to an electric breast drill which can be operated at several speeds, and is so arranged as to have a small size and weight; the said apparatus is of a very responsive character, and is of a most convenient use, and we are enabled to employ a motor of small power.

The said apparatus comprises an electric motor whose shaft is situated in the direction of the drilling, and transmits its motion by means of bevel gearing to a transverse shaft upon which we may slide by hand a pinion provided with pointed members, thus bringing it into gear engagement, according to the desired speed, with any one of the circular and concentric rows of holes in a disk which is connected with the member holding the chuck in such manner that it may be axially displaced to allow the change of position of the said pinion provided with the pointed members, whereby the speed of the apparatus may be suitably changed.

The appended drawing shows by way of example an embodiment of the invention.

Fig. 1 is a vertical section of the drilling apparatus.

Fig. 2 is a vertical section on a plane perpendicular to the section shown in Fig. 1.

Fig. 3 is a half plan view of the frame alone.

Fig. 4 is a partial vertical section analogous to Fig. 2, relating to a modified construction.

1 is the armature of an electric motor whose field-magnets are mounted on the main frame 2. This latter is terminated at the upper part by a boss 3 upon which is pivotally mounted the usual breast plate 4.

The motor shaft 5 carries at the upper part the cooling flanges 6 and at its lower part the commutator 7 coacting with the brushes mounted on the support 8 which is interposed between the frame 2 and the main body of the machine 9, which has the form of an incompletely closed frame. At the lower end of the shaft 5 is mounted a bevel pinion 10 engaging a pinion 11 keyed to the shaft 12 whose section is not circular, and may have a square or like shape.

The shaft 12 is provided with journals No. 257,980, and in. France March 5, 1927.

mounted in ball bearings which are held in place by the plugs 13 screwed into the frame 9, and it carries a pinion 14 provided with pointed members and slidable thereon, as

will be further specified, thus coacting with one of the concentric rows of perforations formed in the disk 15, whose central part has a concave shape for engagement with the pinion 11.

The disc 15, which projects upon the opposite sides of the frame 9, is provided with an axle 16 which is bored in its center for the insertion of a spring 17 which acts on a. key 18 having the form represented in Fig. 1 and engaged in the diametrically opposite slots in the said axle and of the member 19 which carries the chuck 20 and surrounds the said axle.

The member 19 is mounted in a ball bearing which is fitted into the lower part of the frame 9 and is rotatable in a socket 21. The sa d member is provided at the upper part with a cap 22 which is secured by two screws and against whose end the key 18 is urged by the spring 17 In this manner the rotation of the disk 15 is imparted to the chuckcarrymg member 19 through the medium of the axle 16 and of the key 18.

The pinion 14 being in the position herein represented, which corresponds to the slowest speed of the said chuck, if the operator desires to use another speed, he presses down the disk 15 in such manner that its axle 16 will descend in the bore of the member 19,

thus compressingthe spring 17, andhe then displaces the pinion 14 by sliding item the shaft 12 until it coincides with the proper row of perforations in the disk 15. He then leaves the said disk, and the latter will autoq matically return to its initial position of en- 2 gagement with the pinion 14. The said arrangement of the disk and its axle will thus form a very simple device, since we are thus enabled to eliminate the usual additional abutment placed between a stationary and a rotating member.

We may employ other arrangements whereby the geared parts may be separated,

for the operation of the change-speed device.

One of these modified constructions is shown in Fig. 4.

In this figure, the disk 15 and the chuck 20 are mounted in combination on the same axle n3 rotatable in the ring 2a which may be raised or lowered with reference to the support 9.

The connection between the said ring and the support may be effected as herein represcntedby screw thread, or by a bayonet device or like arrangement.

As before, when the disk 15 is in the upper position, it engages the pinion 14: (not snown); when the disk is lowered by unscrewing the said ring, whose thread is contrary to the one screwing upon the chuck 20, the pinion l fmay be moved so as to change the speed.

The said drilling apparatusvis provided with two handles 23 which may be variously inclined with reference to the main body and may be held in any chosen position; said handles are pivoted to the member 8, but it is obvious that they might be pivotedto the frame 9.

This latter preferably consists of pressed steel, and it is properly centered on the intermediate member 8, but it is evident that this centering can be dispensed with and themain body can be upwardly extended so as to form a sort of closed frame carrying the motor. the transverse shaft 12, and the chuck-holding member.

Obviously, the said invention is not limited to the details ofthe apparatus herein described by way of example, and without departing from the spirit of-the invention the form, disposition and assemblingof the aliens parts may be suitably modified.

Having thus described our apparatus, what we claim as new therein, and our own invention, is:

In an electric breast drill, the combination of a frame having at one end a seat adapted to receive an electric motor and at the oppo site end a socket, the axis .ofwhich is in line with the axis of the electric ;motor. a pinion secured to the shaft 'of. the electric motor, a transverse shaft journaled: in the frame a bevel gear secured to this shaft on one side of the axis of the said socket, and adapted to be engaged by said pinion of the electric motor a pinion-wvith pointed teeth slidableonqthe said shaft on the opposite side relatively to the said axis. a bearing in the said socket, the said bea ring and'the said sockethaving threaded parts adapted tobe screwed together, a tool-holdingshaft and a disc securedtot-his tool-holding shaft and provided with several rows of holes-adapted to engage the pointed teeth-,;t;hesaid-toolholding ishaft being-journaledgin the said hearing so as to rotate but not to slide inthe axial direction relatively to theisume.

In testimony we have hereunto afiixed our signatures.

CAMILLE CONTAL. PIERRE KRETTLY. 

